1. Field of the Invention
The present invention relates to an ultrasound surgery system for performing a surgery for therapy using ultrasound vibration.
2. Description of the Related Art
In recent years, ultrasound surgery systems for performing surgeries for treatment, such as dissection and/or coagulation, of a site of lesion utilizing ultrasound vibration, using a handpiece with an ultrasound transducer mounted therein have been used.
For example, Japanese Patent Laid-Open Publication No. 7-303635, which is a conventional art example, discloses a system that performs constant current control using phase-locked loop (PLL) control that drives an ultrasound transducer mounted in a handpiece while tracking a resonant frequency so as to, even if a load varies, drive the ultrasound transducer at the resonant frequency. Also, the related art example discloses a configuration in which switching of a characteristic of a low-pass filter is performed so as to perform stable PLL control.
Where an ultrasound transducer includes a langevin transducer that includes a plurality of annular ultrasound vibration elements fastened together via a bolt, some variation in characteristic occur among respective products.